Field of the Invention
The present invention generally relates to an actuator for rifle butt stock adjustment for shoulder fired firearms and more particularly concerns adjustable butt stock mechanisms that enable firearm users to establish rapid and precision adjustment of the length of a rifle as desired for a comfortable fit of a firearm stock with the anatomy of the user and conditions—e.g., in the event close quarter combat conditions warrant the use of a rather short and compact shoulder fired weapon. Such firearms may include rifles such as the AR15, M16 and M4.
Description of the Related Art
U.S. Pat. No. 3,348,328 to Roy teaches a mechanism for an extendible, telescoping rifle butt stock. A butt stock body and lower receiver extension are axially movable with respect to each other by movement of the lower receiver extension in the bore of the butt stock body. Roy teaches that a spring-loaded lock pin holds the rifle butt stock at a particular length. To change the length, the user must first disengage the lock pin by squeezing a lever upward toward the base of the butt stock or pulling the lever down away from the butt stock while simultaneously sliding the butt stock relative to the lower receiver extension with a relative pull or push force. The squeeze action cannot practically be carried out while the weapon is in a firing or ready position. The pull-down action risks pinching the user or entrapping the user's glove when the lever is returned to the lock pin engaged position and also requires an unnatural, forced underhand grasp of the lever.
U.S. Pat. No. 8,474,169 to Cottle discloses a cammed lock pin disengaging mechanism which the operator must rotate left or right about a vertical axis. Once the lock pin is disengaged, the stock length can be changed by sliding the buffer tube relative to the butt stock. The buffer tube is locked in place again when the operator rotates the disengaging mechanism left or right back to the lock position. The locking, length change and relocking is not easily carried out while the rifle is in the firing or ready position.
In one prior art implementation, see FIG. 4, a lever 44 in a hollow of butt stock 11, may be squeezed, thereby pulling lock pin mechanism 55 downward and disengaging a lock pin from the buffer tube 2. While squeezing, the operator must push or pull the butt stock relative to the rest of the rifle and then release the lever to lock the butt stock in position on the buffer tube. The squeeze action and push or pull actions cannot practically be carried out while the weapon is in a firing or ready position and the user cannot easily maintain a consistent sight picture.
Accordingly, there is a need to overcome the shortcomings of these prior devices to promote a consistent sight picture and ability to extend and retract the butt stock while keeping the rifle steady and in a sighting or firing position.